Oman's ruler has returned to the country after reportedly undergoing medical checks in Germany.

A statement from Oman's royal court, carried by the country's state-run Oman News Agency, said Sultan Qaboos bin Said returned to the country on Tuesday.

The statement described Sultan Qaboos' visit as one to conduct routine medical checkups "which were crowned with success by the prospective good results."

The 75-year-old, Western-backed sultan is the Middle East's longest-reigning monarch, who came to power in 1970 in a bloodless coup. He has taken several medical trips to Germany in recent years, at one point staying for eight months from July 2014 to March 2015. Officials offered no specifics about why he spent so much time there that visit.

Sultan Qaboos has no immediate heir.